Apparatus for the electrolytic extraction of metals.



PATENTED SEPT. 4, 1906.

0. F. CARRIER, J11. APPARATUS FOR THE ELECTROLYTIC EXTRAGTIONOP METALS.

APPLICATION TILED JAH.30,1905.

A T J .N N 8 WW Cw am A w W a Y j 8 W UNITED @TATES PATENT @FFIGE.

COURTLA ND F. lARRlER, JR, OF ELMIRA, NElV YORK, ASSIGNOR TO ELMIRAliLECTlii)CHEMICAL COMPANY, OF ELMIRA, NEW YORK.

AFPARATUS FOR THE ELECTROLYTIC EXTRACTION OF METALS.

Specification of Letters Patent.

Patented Sept. 4, 1906.

Application filed January 30,1905. Serial No. 243,184.

To all Ill/b07121 it Hm/y con/(107 12,:

Be it known tliatl, UoUR'rLAN'n F. CAR- nLaR, J12, a citizen of theUnited States, residing at Elmira, in the county of Chemung and State ofNew York, have invented certain new and useful Improvements in ratus forthe Electrolytic Extraction of Metals, of which the following is aspecification.

My invention relates to improvements in a paratus for carrving on theprocesses for tl fe electrolytic extraction of metals which re lighterthan the electrolytes from which the are separated; and my object is toprovide certain novel features in the construction of such a paratuswhereby the efhciency and facility 0 working such processes will beincreased and the cost of producing these nietalswill be diminished.

I attain my object by the arrangement of the several parts of theapparatus, as illustrated in the accompanying drawings, in which Figure1 is a longitudinal vertical section of an electric furnace embodying myimprovements, and Figs. 2 and 3 vertical transverse sections of the sameon the lines a a and b b in Fig. 1 lookin to the right.

Like numerals designate fike parts in the several views.

Referring to the drawings, 1 indicates a large pan which is set 111 amass of masonrv This pan is best made of cast-iron and is preferablv ofrectangular form. The

middle portion of the bottom is raiscdis'omewhat above the level of thetwo end portions, this raiscd'portion extending across the entire' widthof the pan, forming a shallow portion at the center and depressions ofgreater depth at each end. The other parts of the furnace up to andncluding 18 are supportod within this pan by means of iron cleats 3,cast wit h the pan or riveted to the sides or by other uitable moans.

1-: raised portion of the pan is lo- Lili anorie-compartment, which isin- :i i rtzirm'ular frame 4, preferably of T is 1 rams lined with basicmaas macis or other material, not be atii ed by the electrolyte n elfduring the process.

Ul ill (.1 k

upiicd with feed- .1 sn pp of electrol provided for the Appaclosed atthe top bv a" l "lizil s1 imlar to the- .uimble material for l theanodes is graphite. To protect the anodes from the action of the gases,they are l surrounded by sleeves 10 of the same. material as the lining.The feed-holes are covered with small slabs 1 1 of this same material orof soapstone. The number of anodes used may vary within the limits ofpracticability, according to the capacity desired, the width of thefurnace being increased to accommodate the desired number. At the backof the furnace is located a port 12 for conducting off the gases evolvedduring the process.

The cathodc-compartments are two in anode compartment. Each cathode com-I partment consists of a rectangular metal box 13, preferably ofcast-iron, which is closed upon all sides except the bottom, forming arectangular bell. The cathode itself consists of a flat iron plate 14,the lower surface of which is slightly inclined upwardly from the sidestoward the center and toward one end. This plate istsupported by a heavylug 15, which is insulated from the bell 13 bv a sleeve .16, which maybe of porcelain or other suitable material. The electrolyte 17 is onlydeep enough to touch the entire lower surface of the cathode. Just belowthe surface of the electrolyte is located a small iron pipe 18, whichextends entirely around the compartment. This serves to carrycooling-water, the purpose of which will be explained later. The ironpipe 19 is to carry the liquid metal from the furnace. This pipe isinsulated from the pan and carried from the furnace by means of theconcentric sleeve 20, which is fastened to the pan. Both pipe and sleeveproject several inches from the furnace. At the outer end the spacebetween the pipe and sleeve is filled with a ring 21 of suitable packingmaterial, such as fire-clay. In the portions of the pan remainingbetween the cathodc-compartmcnts and the ends are located the means ofcirculatingithe metal or alloy with which the pan is partially filled.Each consists of a rectangular mass of iron 22, cast hollow, which iscaused to move slowly up and down by means of the crankshafts 23. Thetwo pistons are so regulated that while one is thrust downward the otheris drawn upward. In this way the molten metal is caused across theraisedportion of the pan beneath the anode-compartment. At the ends of thepistons are lugs 24, which fit loosely into iron to flow back and forthland! or steel guides 25 on the sides of the pan and constrain thepistons to move in a vertical plane.

Beneath the ends of the pan are gas-burners 26 for-the purpose olheating the apparatus on startin, and to keep it hot during anytemporary interruption of the current, the passage of which under normalWorking conditions may supply suilit'ient heat to keep the contents ofthe furnaccin a molten condition, or they may he used as a continuoussource of heat during the action of the process. l/Vhere gas is notavailable, ordinar lire-places may he used instead of the moreconvenient gas-burners.

The relation of the various parts to one another and their specialadi'antagcs may he much more clear-l; understood by considering aconcrete example of the Working of the apparatus. The metal lighter thanthe electrolyte from which it is extracted that has the largestcomn'iercial demand is sodium, and the cheapestava ilahle source issodium chlorid or common salt. We will therefore consider the productionof that metal from salt by means of this improved apparatus. Assumingthat the various parts are arranged according to the precedingdescription, We proceed as follows:

The anode 9 is connected with the positive terminal of a source ofelectricity and the two cathodes 14' with the negative terminal. Thefurnace is heated to over 350 Centigrade by means of the burners 26. Thepan is now filled Witha hodjvof molten lead 27, sufficient to form ali'uid seal at the bottom of the three electrolh'tic compartments. Tin,cadmium, or certain alloys 0. ow melting-point may also be used; hutlead is the cheapest metal which will perform the desired functions. Thecathode-compartments are then filled with molten caustic soda (sodiumhydroXid) or other suitable electrolyte to the level of the lowersurface of the cathode 14. The caustic soda and lead are readil kept ina molten condition hy means of the burners. The anode 9 is lowered untilalmost in contact with the lead, salt is piled around it, and thecurrent started. The pistons i'or circulating the lead must also he setin motion. At first the current should not he allowed to pass to thecathodes, but should he conducted away by means of temporary contactswith the pan. if this is not done, the lead will he attacked in thecathode-compartment. for there Will not be enough sodium present toprotect the lead.

electric arc which melts the surrouu'ling salt. This requires atemperature of 800 to 900 ccntigrade. As soon as enough salt is meltedto cover the end of the anode the arc will he lhc passage ol the current irom the 'anoce to the lead lorms an anode and cathode, willhereinafter he kn n as the secondary anode and secoi'idar v cathode. Theprimary electrodes will he referred to simply the anode and cathode,respectively.

The chlorin escapes as a gas and isconveyed away through the port 12.The sodium is absorbed by the molten lead-forming an alloy. Theadvantage ofhavi the sodium During tais period The anode 9 and thecathodes 14' n I O set free in this manner rests in t is fact that puresodium would at onoe he attacked by the electrolyte. The alloy of sodiumand lead, however, is attached to a lesser degree" than pure sodium.Therefore by "thus alcsorhing the sodium as rapidly asit is separated bythe current the loss by recombination is reduced to a minimum. The alloyis then carried toward the cathode by means of the circulating-pistons.The function of the lead is to act as a bipolar electrode in series withthe primary electrodes, its surface, therefore, being negative acting asa cathode nearest the source of positive current and positive acting asan anode'nearest th source of negative current. It is, however,nossilole for the sodium to alloy with the lead, thus being able to passthrough the lead, while the electrolytes have not this power. Thefunction of the lead, in brief, is

to convey the sodium and the current from the anode to the cathodecompartments While holding the electrolytes in their respectivecompartments. y

in the cathode-compartment the current decomposes the caustic soda, lil:"sting sodium at: the cathode 14 &Ild h:\ (il'OT;: l ions at the surfaceof the lead or secondar anode. The allinit between hydroxyl ions andsodium is greater than between hydroxyl ions and lead. Therei ore sodiumdissolves in preference to lead and the caustic soda is reproduced. itwill thus he seen that While caustic soda is constantly decomposhd therewill be just as much remaining at the end of the i the salt decomposedin the anode-compartextinguishcd: hut the passage of a large currentthrough the salt will continue to melt it secondary anode to thecathode. until the conmartment t. tilled to :h rc

ment. The caustic soda is then merely a medium for transferring thesodium from the The advantage oi separating sodium in this manner restsin the fact that it is liberated in an electrolyte free from the actionof the oxidizing substances set free at the anode. This is made possibleby the absolute separation of the electrolytes of the anode and cathodecompartments by means of the molten lead. The lead thus performs thefunction of a semipermeable diaphragm, but with greater efficiency thanthe usual forms of diaphragnis, all other forms of which permit portionsof the electrolyte, as well as the desired product, to .pass through.

The collection of the sodium liberated at the cathode has always been amatter of considerabie dilliculty in practice. One of the chief objectsof this invention is to reduce these difficulties. The sodium collectsupon the surface of the electrolyte 17, and therefore has a tendency toform bridges between the cathode 14 and the bell 13. In" case such abridge is formed the current is short-circuited between the secondaryanode and the cathode, and current thus lost will i produce no sodium atthe cathode. To prevent this, the small iron pipe 18 is extendedentirely around the bell just below the surface of the electrolyte. Whencooling-water is passed through this pipe, the portion of electrolyteimmediately surrounding the pipe will be solidified. This solid layer isa non-comluctor and will prevent stray currents from leaking across fromthe cathode to the bell, as well as prevent sodium bridges from comingin contact with the iron walls of the bell. The loss due to shortcircuits and stray currents is thus reduced to a minimum.

- The most serious source of loss, however, is

due to the oxidation of the sodium between the time it is liberated andits formation into I or hydrogen.

ingots. To exclude the atmosphere, use is made of the closed bell 13.,This is kept filled with a gas which will not react to any great extentwith sodium, such as nitrogen The sodium as it is liberated moves alongthe inclined surfaces of the cathodes to the overflow or draw-offpipes19, whence it isconveyed by iron pipes to a suitable vesselcontaining melted paraffin, below the surface of which the pipes diplThe sodium sinks to the bottom and can thus be collected without havingbeen exposed to any oxidizing atmosphere at any moment from the time itwas liberated till enough has collected to pour into the molds.

The circulating device for the lead is made as simple as possiblctoavoid the difficulty of making sliding .joints, which will remain tightthrough a great variation of temperature. instead of a. piston asordinarily constructed use is made of pistons in the form ofloosely-fitting lloats or plunger-s, which act merely by displacing avolume of load equal to the submerged volume of the piston. The loaddisplaced by the downward movement of one piston is provided for by thesi multaneous upward movement of the second. In flowing from one to theother cathodechamber the lead must pass beneath the anode-chamber andperforms the alternate function of secondary cathode and anode, asalready described. The lesser depth of the lead where it flows over theraised portion of the pan beneath the anode-compartment causes anincrease in the velocity, thus removing the sodium more rapidly from theaction of the anode electrolyte. The rate at which the pistons move isgoverned by the amount of sodium liberated in the anodechamber (thus onthe number of amperes used) and the percentage of sodium which the leadcan absorb with maximum efficiency. This percentage varies from four percent. to six per cent. The lead may also be circulated by other meansthan the pistons, as shown.

' I do not wish to be confined to the production of sodium by myinvention, as I may employ the invention for the production of any othermetal which is lighter than the electrolyte from which it is separated,nor in the production of sodium do I wish to be confined to the use ofpure common salt in the anode-compartment and pure sodium hydroXid inthe cathode-compartments, as I may use some other salt or mixture ofsalts in one or both compartments.

What I claim as new, and desire to secure by Letters Patent, is

1. An electrolytic apparatus comprising an anode-compartment lined withrefractory and non-conducting material, cathode-compartments at oppositesides thereof having interior metallic wall-surfaces, said compartmentsbeing supported with downwardlyopen ends above a body of molten metalwhich acts as a seal and also forms part of the electric circuit betweenthe compartments, electrodes in the anode and cathode compartments, andmeans for producing a flow of the molten metal back and forth betweenthe anode and the cathode compartments.

2. A11 electrolytic apparatus comprising an anode-compartment,cathode-compartments at opposite sides thereof, a pan containing amolten metal above which the compartments are supported with theirdownwardly-open ends sealed by said metal, said pan being shallow at thecenter beneath the anode-compartment and deeper at the ends, means forproducing a flow of the molten metal back and forth between the anodeand the cathode compartments, and electrodes in the anode and cathodecompartments.

3. An electrolytic ap aratus comprising a pan resting over a iire- 0X ateach end and having its bottom raised at the center, ananode-compartment supported over the pan with its downwardly-open endabove said raised portion, cathode-compartments at opposite sides of theanode-compartment with their downwardly-open encis above the deeperportion of, the pan, a molten metal in the pan sealing the ends of saidcompartments, and means for producing a flow of the molten metal backand forth between the anode and I I said raised portion,eathodecompertments at opposite sides of the anode-compartment withtheir downwardly-open ends above the deeper portions of the pan, amolten metal in the pan sealing the ends of said compartments,riisplaeement-plungers at each end of the pan etheeentthecathode-compartments, and means for reciprocating said plunger-s inopposite directions to produce e flow of the molten metal back and forthbetween the anode and the cathode compartments.

5. An electrolytic apparatus comprising anode and cathode compartmentssupported with their open ends downward and sealed by a molten metal,displacement-plungers acting upon said body of metal at oppositesides ofthe compartments, and mezms'fo reciprocating said plnngers in oppositeCl? tions.

6. In an electrolytic apparatus, nation, with an anode-come, cathodecompartment colnprisin metallic bell said compartments ported with theiropen ends ilOWIP. Y .t sealed by a body of molten metal. 5

7. In en electrolytic apparatus e oath con'ipartment romprsing :2 closedbell, mi electrolyte contained therein, an eleotroele having its lowersurface in Contact with surface of the electrolyte said surface of theelectrode being inclined upward from the sides to the center and fromone end t ward the other end, and e draw-oh" pipe having orifice at thesurface of the ele trolyte adjacent the elevated end 01 the el node. 4

in testimony whereof the 1'' e 4: nature in presence of two witCOURTLAND F. oer-mien, JR; Witnesses:

M. VERBEOK,

A. S. DIVEN.

